Fresnel Lens Coupling Surface Light Absorbing Coating
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Solution Overview
Problem
Fresnel lenses formed by molding often generate flares in the image due to light transmission through the top portion, which degrade image quality, and existing techniques fail to effectively suppress these flares.
Innovation Solution
A Fresnel lens design featuring concentrically formed protruding lens portions with a light absorbing portion on the coupling surface along the optical axis, which absorbs light and prevents flare generation, combined with a manufacturing method that includes masking, exposure, and molding to ensure precise placement of the light absorbing material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a Fresnel lens is formed by molding through injection molding, then the lens can be efficiently manufactured, but light is transmitted through the top portion causing flare that degrades image quality
Solution Approach 1:
The invention extracts and removes the harmful light transmission function from the top portion of the lens by applying a light-absorbing coating to the coupling surface. This selectively eliminates the harmful effect (light transmission causing flare) while preserving the beneficial function of the rest of the lens structure.
Solution Approach 2:
The invention applies different optical properties to different regions of the lens. The coupling surface (top portion) is treated with a light-absorbing coating to prevent flare, while the rest of the lens maintains its original transparent and refractive properties for proper light transmission and focusing.
2Reliability
If existing techniques (PTL 1 to PTL 8) are applied to enhance image quality, then some image quality issues are addressed, but the specific flare generated by the top portion of lens portions is not suppressed
Solution Approach 1:
The invention converts the harmful light transmission at the top portion into a beneficial effect by using the light-absorbing coating to actively suppress flare. The harmful transmitted light is transformed into absorbed light, preventing it from reaching the image plane and causing degradation.
3Reliability
If a light absorbing portion is provided on the rise surface, then image quality is enhanced according to PTL 1-7, but the flare from the top portion (coupling surface) is not addressed
Solution Approach 1:
The invention specifically targets the coupling surface (top portion) with a light-absorbing coating, applying the light-absorbing property locally where it is most needed to prevent flare, while leaving other regions with their original optical properties intact.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design effectively suppresses flare generation by absorbing light at the top portion, improving image quality by reducing unwanted light transmission and enhancing the optical axis alignment.
Implementation Method 1
a light absorbing portion is provided in a position along an optical axis of the Fresnel lens which passes through the coupling surface
Data Source
Figure 1~2
Figure 3
Figure 4A
AI summary
There are provided a Fresnel lens and a method of manufacturing the Fresnel lens which can suppress a flare which is generated in an image visually recognized through the Fresnel lens so as to extend toward a center of a lens. A lens surface (24) and a non-lens surface (26) are formed in each of lens portions (22). The non-lens surface (26) includes a rise surface (26a) and a coupling surface (26b). The rise surface (26a) is a surface along an optical axis of a Fresnel lens (1). The coupling surface (26b) is a surface which is formed on a top portion (22a) of each of the lens portions (22) and couples the lens surface (24) of the lens portion (22) and the rise surface (26a) of the lens portion (22) to each other, and which has a width extending in a radial direction of the Fresnel lens (1). A light absorbing portion (12) is provided in a position along the optical axis of the Fresnel lens (1) which passes through the coupling surface (26b).